Automotive vehicles with internal combustion engines are typically provided with both a starter motor and alternator. In recent years, a combined alternator and starter motor has been proposed. Such systems have a rotor mounted directly to the crankshaft of the engine and a stator sandwiched between the engine block and the bell housing of the transmission. During initial startup of the vehicle, the starter/alternator functions as a starter. While functioning as a starter, the starter/alternator provides a sufficient amount of starting torque to rotate the crankshaft of the engine before the cylinders are fired. After the engine is fired, an amount of engine torque is provided to the crankshaft from the combustion process in the cylinders. After the engine is started, the starter/alternator is used as a generator to charge the electrical system of the vehicle.
As the vehicle is traveling, the transmission changes gears to prove a predetermined ratio between the engine and powered wheels of the vehicle. Also, when quick acceleration is desired, engine speed (RPMs) typically increase slowly and thus power output increases slowly. Thus, during gear change to obtain a desired quick acceleration, the engine torque may not be sufficient to provide desired acceleration. Because the power output is slow to match the desired power, noise, vibration and harshness (NVH) increases during such times. Automakers are constantly striving to reduce undesirable NVH.
It would therefore be desirable to provide increased power or decreased power to control speed and reduce the NVH during gear shifts.